Just updated /etc/config/nss as posted here

root@OpenWrt:~# cat /etc/config/nss
config nss_firmware 'qca_nss_0'

config nss_firmware 'qca_nss_1'

config nss 'general'
        option enable_rps       '1'
        option enable_log       '1'

and nss is working. So, there is no need to include the fstool commit

root@OpenWrt:~# cat /proc/interrupts | grep nss_queue
 48:       4113    2513130          0          0 GIC-0 412 Edge      nss_queue0
 49:          0          0      28283          0 GIC-0 413 Edge      nss_queue1
 50:          0          0          0      90273 GIC-0 414 Edge      nss_queue2
 51:      11297          0          0          0 GIC-0 415 Edge      nss_queue3
 59:      26665          0     563758          0 GIC-0 425 Edge      nss_queue0
 60:          0          0          0          0 GIC-0 426 Edge      nss_queue1
 61:          0          0          0          0 GIC-0 427 Edge      nss_queue2
 62:          0          0          0          0 GIC-0 428 Edge      nss_queue3